Method of tamping bla



(No Model.)

J. L. L. KNOX. METHOD OF TAMPING BLAST HOLES.

No. 314,585. Patented Mam 31 1885.

UNITED STATES PATENT OFFICE.

JoHN L. L. K ox, 'o'F ALLEGHENY, ASSIGNOR .TO THE KNOX ROCK BLAST- I-Ne COMPANY, or PITTSBURG, PENNsYLvANIA;

METHOD OF TAMPING BLAST-HOLES.

SPECIFICATION forming part of'Letters Patent No. 314,585, dated March 31, 1885. Application filed April .7, 1884. (No model.)

-required size at the bottom of th e'hole and the tamping directly upon the top of the charge. Another method has been to place the charge 'atthe bottom of the hole and the tamping' some distance above the charge, thus leaving a greater or less unoccupied space between the charge and the tainping. The first method is subject to the objection that almost the whole force of the explosion is confined to the immediate vicinity of the bottom of the hole, and the rock is thereby torn to pieces in the latter place, while only affected to a slight degree near the top of said hole. In consequence, also, of this a proportionately heavy charge is required to effect a given result. The second method spoken of is of no practical benefit, because the substance used. in tamping has nothing to rest upon, and must consequently be of such depth as that the friction of its lower part against the sides of the hole may be sufiicient to sustain it in place under the heavy blows of the hammer necessary to complete the operation. The result of thisis that a large portion of the hole is filled with the;

, tamping, and all this portion is practically uncharge and tamp the blast-hole aslto expose the sides. of the blast-hole throughout their length (asnear as practicable) to the direct action'of the explodent.

The particular object of the invention is to eflect this general object where the charge is very small in proportion to they depth and area of the hole.

The'particular application of the invention is to the improved method of blasting described inLettcrs Patentissued tome January 8, 1884, No. 291,606. In said patent a blast hole 'isdescribed having oppositely-located longitudinal equilateral two sided grooves, and the force of the cxplodentis spent in the direction of a plane bisecting thegrooves.- In this meth- 0d of blasting comparatively small charges of explodent are used in relatively large lblastholes. It is necessary to make these small charges do duty as near as possible throughout the whole length of the blast-hole grooves. To accomplish this I charge and' l- -tamp. the holes in the manner hereinafter described and shown.

In the accompanying drawings,Figure 1 represents a longitudinal median section of the blast-hole, showing the position of the charge and tamping; Fig. 2, a cross-section of the same, and Fig. 3 a cross-section of a hole having four longitudinal grooves. I

Similar letters of reference indicate corresponding parts throughout the different views.

A is a blast-hole of any required depth or size, provided with oppositely-located twosided equilateral longitudinal groovesa. B

is a rod in diameter somewhat less than the short diameter of the blast-hole, preferably sharpened at one end, and in length equal to that of the blast-hole less the required space for tamping.

- The charge of powder or other explodent may be placed in position in any of three ways, to wit: first, a portion of the powder may be placed in the hole, the sharpened end of the rod driven to the bottom of said hole,and the remainder of the charge dropped down the grooves; or, second, the whole charge may be placed in the hole and the rod then forced to the bottom; or, third, the rod may be first placed in position and the powder dropped in at the top of the hole. It will thus be seen that by this method of cl'larging' and tamping the following combined advantages accrue: first, all urmeccssary space in the blast-hole is disposed of; second, the explodent is so distributed as to art with equal force and simultaneously throughout the length of the blast-hole; and, third, the space necessary for tampingr is reduced to a minimum. It may also be added that in the method of blasting hereinbefore referred to, and described in said Letters Patent issued to me, the present improvement in charging and tainping is the only way known to me in which said'method may be used with rod extending to within ashort distance of its top, distributing the explodent between the rod and the sides of the hole, and tamping at the top of the hole and upon the upper extremity of said rod, as and for the purposes described.

2. The within-described method of charging and tainping a blast-hole having oppositely-located two-sided equilateral grooves throughout its length, which consists in inserting in the hole a rod somewhat less in thickness than the short diameter of the hole and somewhat less in length than said hole,

distributing the explodent throughout the groovesand tamping upon the top of said rod, substantial] y as and for the purposes set forth.

J N0. L.- L. KN X.

\Vitnesses: I

B. MOKENNA, JOHN TETLEY. 

